Pullout Performance of Geogrids with Different Junction Strength: Fid-Bau Portal

Pullout Performance of Geogrids with Different Junction Strength

Mahmood, T. / Hatami, K. / Ghabchi, R. / Zaman, M. M.

As part of an on-going study at the University of Oklahoma, the influence of geogrids junction strength on their in-aggregate performance was examined using pullout tests. One objective of the study was to determine to what extent the junction strength is a governing factor in the serviceability and stability of reinforced aggregate bases. This paper reports the results of in-isolation and pullout tests on two extruded and two non-extruded geogrid products in ODOT Type-A aggregate which is a dense graded aggregate with low permeability. Pullout tests can provide useful information on the in-aggregate performance of geogrids in a region outside the stress bulb directly beneath the tire pressure. This "anchorage zone" could be especially important for the case of extensible geogrids which require comparatively greater deformations in order to mobilize their strength. Pullout test data in this study indicated that the biaxial extruded geogrid with higher rib strength at 5% strain and comparatively larger junction strength values resulted in the largest pullout resistance. In addition, the rib strengths at 2% strain and 5% strain and the ultimate junction strength values were found to be better indicators of the geogrid pullout performance than the ultimate rib strength for both extruded and non-extruded geogrid products.